Improvement in screens of win nowing-mach in es



W. M. WATSON.

Grain Screen.

Patented Oct. 29, 1.861.

Inventor:

Witnesses:

u. PETERS. mum Washingflm. n. c.

UNITED STATES PATENT EEicE,

XVILLIAM MEDD YVATSON, OF TONICA, ILLINOIS.

IMPROVEMENT IN SCREENS OF WlNNOWlNG-MACHINES.

To all whom it may concern.-

Be it known that 1, WILLIAM MEDD -WAT SON, formerly WILLIAM \VATsON, of Tonica, in the county of La Salle and State of Illinois, have invented certain new and useful Improvements in Sieves and Screens Specially Applicable to Machines for Screening and \Vinnowing Grain, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, making part of this specification, and in which Figurel represents a plan, and Fig. 2 a section at the line X X of Fig. 1, of a fanninglnill screen embracing my improvements. Fig. 3 represents a plan, and Fig. 4 a section, of a like screen embracing my improvements in a modified form.

The sieves and screens of winnowing-machines require rapid vibratory and jarring motions, to maintain which, when the sieves and screens are heavy, consumes a great deal of power, besides straining and rapidly wearing out the gearing and the frame of the machine.

If the screens are made of solid bars or rods of metal extending across the frame of the sieve or screen, in that case the quantity of metal required, in addition to the objections arising from its great weight, is too costly.

To lessen both the weight and the cost of the screen, and thus avoid all the objections before mentioned without a sacrifice of any advantage, I have devised the plan of making the series of metal bars that extend across the screen of tubular or crimped or corrugated thin sheet metal instead of solid round or angular bars. I prefer tinned or galvanized sheet-iron; but other sheet metal will answer the purpose. This mode of construction renders the screen comparatively light and also admits of the grooves and ridges on the surface of the screen being made comparatively deep with but little addition to the weight of the sieve or screen, which cannot be done when solid cylindrical or prismatic bars are used, as their increase of Weight is in the ratio of the square of their diameter, so that to double the depth of the groove by doubling the diameter of the bar would quadruple the Weight and cost of the bar,whereas to double the depth of the groove by means of my improvement would in no case involve more than doubling the weight of the bar, Which originally is never more than a quarter and seldom more than onetenth of the Weight of a solid prismatic or cylindrical bar giving the same depth of grooves.

In the drawings, Figs. 1 and 2, a represents the side pieces, and a the end pieces, of the frame of a screen. 1) represents the screen rods or bars, made of thin sheet netal bent into a trough or spout like form, having two flat sides standing at an angle of about eighty degrees of a circle to each other, these sides being united at their adjacent edges by a sharp curve to avoid the injurious straining or breaking of the metal that would result from the bend being a sharp angle instead of a curve. Figs. 3 and 4 represent a screen having rods with curved instead of flat sides, being in other respects similar to those represented in Figs. 1 and 2. Figs. 5 and 6'represent a sieve or screen with rods of a tubular cylindrical form.

Numerous other forms of sheet-metal rods, it is obvious, can readily be made by any competent workman if they should be deemed preferable for any purpose to those above shown.

The rods are secured to the frame by inortises made in the inner sides of the end pieces a to receive the ends of the rods, which being inserted in the mortises are held there by uniting the end pieces by means of the side pieces a. The slots between the bars must be made as wide as possible without leaving room for the smallest grains of seed it is desired to retain to fall through, because the Wider these slots can be made and still retain the grain the more thoroughly will the grain be cleansed from impurities; but as different kinds of Wheat have kernels of diiferent diameter the width of the slots must be about one-thirtieth of an inch less than the diame ter of the smallest sound kernels of the wheat to be cleansed. The convergence of the adjacent sides of the rods toward the slot causes oats and chess to arrange themselves in the trough with their long axes parallel to the slot, when they readily drop through, as they are of less diameter than wheat.

On a screen of the usual construction made of wire most of the oat and chess grains roll lengthwise across its meshes and thereby avoid dropping through, remaining With the Wheat; but in deeply-furrowed screens like this long slender seeds must fall into the grooves and become parallel to the slot, when they necessarily fall tl'irough and thus become separated from the Wheat. The great stiffness of these bars, combined with their lightness, renders it easy to make and keep the slots of uniform Width, which is essential to the effective and equable Working of the machine. The grain is passed over the screen in the direction of the length of the grooves.

\Vhat I claim is- 1. The combination of thin metal bars with a frame to form sieves and screens, substantially as described.

2. The method herein described of cleansing grain by passing it over a screen having deep grooves with wide tops and narrow slotted bottoms, substantially as described.

In testimony whereof I have hereunto subscribed my name.

lVILLIAM MEDD WATSON. \Vitnesses:

O. DRYER, J. B. DAKIN. 

